1. Presented by: Dr. Munam Ali Shah
Network Security
Lecture 7
Presented by: Dr. Munam Ali Shah

2. Summary of the previous lecture
We learnt about different types of DoS attacks
We have seen how ICMP can be a victim of DoS attack
Some examples of ping to death and SYNC flood attacks were discussed in detail

3. Outlines Some more discussion on DDoS attacks
Security in Wireless Networks
Types of WLAN and relevant security mechanism
Different ways to secure a WLAN

4. Objectives
To be able to understand why wireless LANs are more prone to security threats and vulnerabilities
To identify and classify among different solutions that can be used to secure a WLAN

5. Distributed Denial of Service (DDoS)
The attacking host is replicated through an handler-agent distributed framework

6. Distributed Denial of Service
Cont.
Two kinds of victims:
agents (compromised using common weaknesses to install DDoS agents code), likely to be identified guilty during the first stage of the investigation
end targets (during the attack)

7. DDoS protection Configure routers to filter network traffic
Perform ingress filtering
Configure traffic rate limiting (ICMP, SYN, UDP, etc)
Deploy firewalls at the boundaries of your network
The filtering system must be able to distinguish harmful uses of a network service from legitimate uses.
Perform regular network vulnerability scans
common and known vulnerabilities could be exploited to install DDoS agents.
Identify the agents that are listening to the handler’s commands
Ingress: the right or permission to enter.

8. DDoS protection
Cont.
Install IDS (Intrusion Detection Systems) capable of detecting
DDoS handler-to-agent communication
DDoS agent-to-target attacks

9. Manifestation of DoS Attacks
Unusually slow network performance (opening files or accessing web sites)
unavailability of a particular web site
inability to access any web site
dramatic increase in the number of spam s received.
Manifestation is an indication of the existence.
US-CERT Established in 2003 to protect the nation's Internet infrastructure, US-CERT coordinates defense against and responses to cyber attacks across the nation.

10. Security in Wireless Network
Due to its nature, wireless Networks are more prone to security threats and vulnerabilities.
Since, the medium is air (radio waves), it cannot be physically protected.

11. Wireless LANs IEEE ratified 802.11 in 1997. Also known as Wi-Fi.
Wireless LAN at 1 Mbps & 2 Mbps.
WECA (Wireless Ethernet Compatibility Alliance) promoted Interoperability.
Now Wi-Fi Alliance
focuses on Layer 1 & Layer 2 of OSI model.
Physical layer
Data link layer

12. 802.11 Components Two pieces of equipment defined: Wireless station
A desktop or laptop PC or PDA with a wireless NIC.
Access point
A bridge between wireless and wired networks
Composed of
Radio
Wired network interface (usually 802.3)
Bridging software
Aggregates access for multiple wireless stations to wired network.

13. 802.11 modes Infrastructure mode Ad-hoc mode Basic Service Set
One access point
Extended Service Set
Two or more BSSs forming a single subnet.
Most corporate LANs in this mode.
Ad-hoc mode
Also called peer-to-peer.
Independent Basic Service Set
Set of wireless stations that communicate directly without an access point.
Useful for quick & easy wireless networks.

14. Service Set Identifiers
The Service Set Identifier (SSID) is the name of the wireless network. A wireless router or access point broadcasts the SSID by default so that wireless devices can detect the wireless network.
To disable SSID broadcasting, use the following path, as shown in the figure:
Wireless > Basic Wireless Settings > select Disabled for SSID Broadcast > Save Settings > Continue
Disabling the SSID broadcast provides very little security. If the SSID broadcast is disabled, each computer user that wants to connect to the wireless network must enter the SSID manually. When a computer is searching for a wireless network, it will broadcast the SSID.
Service Set Identifiers

15. Infrastructure mode Basic Service Set (BSS) – Single cell
Access Point
Basic Service Set (BSS) –
Single cell
Station
Usual configuration for offices.
Extended Service Set (ESS) –
Multiple cells

16. Independent Basic Service Set (IBSS)
Ad-hoc mode
For meetings, conferences or other places where wireless infrastructure (access points) doesn’t exist.
Independent Basic Service Set (IBSS)

17. Joining a BSS When 802.11 client enters range of one or more APs
APs send beacons.
AP beacon can include SSID.
AP chosen on signal strength and observed error rates.
After AP accepts client.
Client tunes to AP channel.
Periodically, all channels surveyed.
To check for stronger or more reliable APs.
If found, reassociates with new AP.
Wireless NICs can measure strength of wireless signal.

18. Wireless Ethernet Standards
Bandwidth
Frequency
Range
Interoperability
802.11a
Up to 54 Mbps
5 GHz band
100 feet (30 meters)
Not interoperable with b, g, or n
802.11b
Up to 11 Mbps
2.4 GHz band
Interoperable with g
802.11g
Interoperable with b
802.11n
Up to 540 Mbps
164 feet (50 meters)
Interoperable with b and g
Bluetooth
Up to 2 Mbps
2.4 GHz band or 5 GHz band
30 feet (10 meters)
Not interoperable with any other
Explain wireless Ethernet standards

19. Components and Operations of Basic Wireless LAN Topologies
Components of a based wireless infrastructure

20. The Components and Operations of Basic Wireless LAN Topologies
How wireless networks operate

21. The Components and Operations of Basic Wireless LAN Security
The threats to wireless LAN security

22. Security in a WLAN in 5 ways
Disabling the SSID

23. Security in WLAN
2. MAC address filtration

24. Security in WLAN
3. Limiting the number of IPs

25. Security in WLAN
4. Enabling the Security mode

26. Security in WLAN 4. Wireless Security mode
Wired Equivalent Privacy (WEP) – The first generation security standard for wireless. Attackers quickly discovered that WEP encryption was easy to break.
Wi-Fi Protected Access (WPA) An improved version of WEP, uses much stronger encryption.
Wi-Fi Protected Access 2 (WPA2) WPA2 supports robust encryption, providing government-grade security.

27. Security in WLAN
5. Internet Access Policy

28. Wireless Access More ways to secure a WLAN Wireless Antennae
Avoid transmitting signals outside of the network area by installing an antenna with a pattern that serves your network users.
Network Device Access
On first connection to the network device, change the default username and password.
Wi-Fi Protected Setup (WPS)
The user connects to the wireless router using the factory-set PIN that is either printed on a sticker or shown on a display.
Software has been developed that can intercept traffic and recover the WPS PIN and the pre-shared encryption key. Disable WPS on the wireless router if possible.
Wireless Access

29. Summary of today’s lecture
In today’s lecture, we discussed how DDoS can be harmful to a network and what countermeasures such as IDS can be used to stop DDoS attacks
We have seen that the nature of wireless network makes it vulnerable to security attacks
We also discusses different ways that can be used to make a WLAN secure

30. Next lecture topics We will continue our discussion on WLAN
Wardriving, which is the act of searching for Wi-Fi wireless networks by a person in a moving vehicle, using a portable computer, smartphone, will also be discussed. 
Discussion on different security attacks on WLAN

31. The End